Go to >> Configuration >> Plugins >> "Google Analytics or Universal Analytics" Here you will put your Google Analytics ID. The plugin causes the code to appear on all the right pages, but if you want to utilize Google's "Enhanced Ecommerce" stuff, there's a premium version available that does much more: https://www.nopcommerce.com/p/2347/dc-google-analytics-with-enhanced-e-commerce-plugin.aspx